Dyeing and printing of polyolefins



, :No Drawing. Filed May United States 3,233,960 DYEIN G AND PRINTlNG Oil POLYOLEFINS Bruno Lonardo, Milan, Italy, assignor to Azienrle Colori Nazionali Ailini-ACNA S.p.A., Milan, Italy 10, 1963, Ser- No. 279,601 Claims priority, application Italy, May 15, 1962, 9,721/62, 9,722/62 9 Claims. (Cl- 8-34) of a vat dyestulf in leuco form or a dispersion of a vat dyestuif;

-.(b Thermally treating the impregnated polyolefin;

() Where a vat dyestuff dispersion is used, then subfooting the thus thermally treated, impregnated polyolefin to reducing conditions to reduce the dyestuff to the leuco form; and

-(d) Subjecting the impregnated polyolefin to oxidation while contemporaneously soaping such polyolefin with a soap solution at its boiling temperature.

The present invention also relates to the polyolefin materials dyed according to, the above mentioned method.

It is well known that articles made from synthetic ma terial obtained by the polymerization of hydrocarbons containing no polar groups, e.g., ethylene, propylene, methylpentene-1,.etc., are most difiicult to dye by the dyestuffs and methods conventionallyemployed because of their lack of affinity for such dyestuffs.

' Such incompatibility to dyeing and the unsatisfactory 'fresults obtained have led to three attempted solutionsto the problem:

(1) Dyeing in mass, using pigments of the synthetic material before shaping or spinning; thishas definite disadvantages because it is necessary that the semi-finished material be produced in the final dye;

(2) A previous partial modification of the material, comprising adding, during the shaping and spinning operation, dyeable substances to the polymer which permits the dyeing of the shaped articles; this technique is disadvantageous in that it is comparatively expensive, yet the final product may not completely be homogeneous.

(3) Substantial modification of either the entire material during the preparation of the polymer, or its surface after it has been shaped, comprising introducing into the polymer molecule atoms other than C and H, or introducing functional groups different from the parafiinic groups (contemplating also the formation of copolymers),

in order to render the material dyeable; this technique has the drawback that the modification of the polymer molecule may lead to a change of the characteristics of the product.

The'present invention goes beyond the solutions described in foregoing items (1), (2) and (3), since it relates only to non-modified polymers, and to the nonmodified polymer portions in the physical or mechanical mixtures together with other materials.

Particularly as regards polypropylene, a very high in compatibility has'be'en shown with respect to dyeing car-v ried out using conventional dyestuffs and dyeing methods;

Results having a practical interest, although very restricted, have been hitherto obtained by the application of vat dyestuffs in dyeing.

The application of vat dyestuffs on textile materials made up of polyolefins, particularly polypropylene, may

be carried out for instance according to the following Patented Feb. 8, 1966 minutes; gradually heating at about 45 C. and carrying 1 on the dyeing at this temperature for about 30-40 minutes while maintaining the pH at between 9.5 and 10 and seeing that an excess of sodium hydrosulfite is always present; rinsing the material with cold Water; soaping for 20-30 minutes at the boiling temperature using a solution containing 2 g./l. of an anionic detergent and between ing the material.

Dyes suggested for use in the above process include 1,2,5,6 diphenyl dithiazol anthraquinone; dibromo anthranthrone; isoviolanthrone; 4,4 dimethyl 6,6- dichloro thioindigo; 5,7,5',7 tetrabromo thioindigo; 4',4" dibenzamido anthraquinon-4,1,10,1" diimido anthranthrone; dibromo-dimethoxy-dibenzanthrone; 1,1, 4,5 dibenzoyl diamino diant'rimide; 2,3',3,2" trianthraquinoyl-l,4',l-diimide; product of the alkaline condensation of 1,3,l",9-diimidoanthraquinonebenzam throne (having respectively the following Oolor Indexes, CI. 67300, 59105, 60010, 73360, 73065, 65225, 59830, 69015, 70800, 69525).

The dyeing process involves a penetration of the dyestuffs in the reduced state followed by fixation in the oxidized state of the dyestulfs in the surface pores of the material.

1 and 2 cc. of 30% hydrogen peroxide; rinsing; and dry- By dyeing according to this method and using appro- 7 priate concentrations of each of the above mentioned dyestuffs, materials are obtained having a very bright shade but with an intensity not greater than those which are of the standard ECE intensity scale. It is clear that such a limitation of the dyeing capabilities severely limits the possible sales potential and marketing of the material. Further, the fastness to rubbing of the dyed materials thus obtained is very low, so that such dyed materials and articles are not suitable for use in home furnishings. Moreover the fastness to organic solvents is so low that drywashing of the colored material is impossible without completely affecting the dyeings. These drawbacks clearly adversely affect the marketing potential of the materials dyed by this technique.

There has now surprisingly been found a method by which it is possible to dye polyolefin materials using vat dyestuffs, whereby the dye product exhibits an intensity 1/1 in the ECB standard scale.

This method comprises:

(a) Impregnating a polyolefin with either a solution ofa vat dyestufi in leuco form or a dispersion of a vat dyestufi;

(b) Thermally treating the impregnated polyolefin;

(0) Where a vat dyestuff dispersion is used, then subjecting the thus thermally treated, impregnated polyolefin to reducing conditions to reduce the dyestuif to the leuco form; and

(d) Subjecting the impregnated polyolefin to oxidation While contemporaneously soaping such polyolefin with a soap solution at its boiling temperature.

'In accordance with one embodiment of this invention, a vat dyestutf in leuco form is applied to the polyolefin material, followed by a heat treatment and a subsequent reoxidation of the dyestuffs while on the material.

7 liter of 30% hydrogen the thus dyed material.

following successive steps:

(a) Impregnationof the polyolefinic material withi a solution of the vat dyestuifin the leuco form, generally" 1 in the presence of additives;

(b) Heat treatment at about 125 C.; I

(c) Oxidation in an'oxidizing bath, preferablyusing hydrogen peroxide, while contemporaneously soaping the polyolefin with a soap solution at its boiling'temperatu'rei Dyeing accordingto this embodiment is desirably car-- ricd out as follows:

Reduction of the dyestuffs in a main vat bath using NaOI-l and sodiumhydrosulfite. in'such amounts and conditions as are generally employed for dyeing cotton;

preparation of an impregnating bath bythe addition of appropirate additives, e.g., those which. facilitate the dye-' stuff penetration and levelling (e.g., diethyl tartrate) and} also anionic dispersing agents i(e.g., the sodium salt of the ligninsulfonic acid) dilution with water containing} sodium hydroxide and sodium hydrosulfite to obtain the- "desired dyeing intensity; eventual thickening-by means of conventional thickening agents; impregnation of the;

polyolefin material at from about lO-60 0; treatment in a hot air:oven at 120-125 C; for-a period of time vary: i

ing from about 1 minute to minutes; rinsing of the: materialiwith cold water;- and simutlaneously oxidizing h and soaping using a solution at its boiling temperature for;

from about -30 minutes, whichsolutionzcontains an anionic detergent, for instance the sodium salt of oleylmethyl-turinic acid (conc.-2 g./l.) or :the sodiumsalt of oleic acid (cone. 2 g. /l.) alonggwith'l to 2 ,ccwpera peroxide; rinsing and drying of In accordance with another. embodimentof the persen't' invention, vat dyestuffs in the dispersedlstate areapplied to polyolefin material, such dyestuffs; are then reduced to a the leuco formfand thereafter are reoxidized Whilei'on the,

' -(b) Thermal treatment at abo utl25 0.;

desirably in the presenceof (c)' Reduction of the dyestufi on the. polyelefin' material in a reducing bath; and a (d); Oxidation in an oxidizing ,bath, preferably with. hydrogen peroxide with contemporaneous soaping treat-: ment at the boiling temperature of, the soap solution;

Preferably, this embodiment is carried-out as follows? Preparation of an impregnating bath by the useof thesuitable amountsrof water, vat dyestuffs (in the form :of

a paste or fine powder havingparticle jsizcs lower than: aboutl micron); and anionicdispersingagents (for: instance the sodium salt of ligninsulfonic acid or, the sodium salt of the naphthalene-sulfonic acid orthe sodium salt of the dinaphthylmethane-disulfonic acid); addition of appropriate, additives e.g., diethyl tartrate, to'facilitate dyestutf penetration and levelling; eventual thickening by; the-aid'of conventional thickening agents; impregnation of the polyolefinmaterial at fromabout 50-60 C.; treatment in a hot air oven at 120-125 C. for a period of time 1 varying fI'Qtll'flbOUiil minute 'to' l0 minutes; reduc tionof the dyestutf on the materialinan aqueousbath 'con-:. taining sodium hydroxide and sodium thydrosulfit'emwhile keeping the pHbetween 9.5 and 10 by gradualfadditions ofnammoniumtacetate;'this reduction occurring while thefl:

;temperature is'maintai ned at from about 50-60-C.,,and I during a period of time of about;30 minutes; rinsing vvith :cold water; soaping for 20-30 minutes with a solution at fits-boiling temperature, this solution containing an anionic detergent (for instance, the sorliunrsalt of oleyl-inethyl- 'taurinic; acid .or the sodium salt of oleic-acidat a con-' 4 a I centration 0f2 gll.) and one to two cc.- per liter of hydrogen peroxide; rinsing anddr'ying of the material In accordance with either of the foregoing embodiments, suitable dyestuffs ,include'anthraq-uinone, indigo,

;tthioindigo,= carbazole,'benzathrone, anthranthrone, and 5 the like, eitherin their simple formyor substituteth or condensed with'one another.-

By the method of this inventio'mit is possible to obtain 7 articles made :from -polyolefin's',: particularly .polypropy-u lene, which are dyed at "1/1 intensity of the Standard EQE scale. s This istmadei possible :by the simultaneous 'usez of,

high temperatures, dispersing'agents, and.,tadditives,-and, inrone embodiment, dyestuffs consisting of particles of- I tiny size: The foregoing results in a-r'emarkable pene-s trationt of the dyestufi. into, the material to be dyed.-

The advantages of the present invention ascompared to be known dyeingtmethodsi arcthe following: a :wideningrof the range} of vat dyestuffs which are usable with; polyolefins,vand.in particular on polypropylene; a re-;- ;markable,increasezinvthe intensities whichimay be 'ob-- tain'ed;:fastnesses. for thedyed articles. which are at'least equal 1 to -and are. generally higher than tthose of articles .dyed according to previously 'known methods; :in particula'r,-'resistances to rubbing at (1/12 intensities are higher thanzthose of articles'dyed at 1/12 Zintensities. according@ to previously known meth0ds.=

vat dyestuffs? may 3150i method of the-invention:

The present invention is also ;directed*ito polyolefinmaterials in'particular polypropylene materials ,(such as fibers, films and other manufactured articles) which have";

been gdyed accordingito the method of this invention:

By comparing the results ofth dyeing obtained according: to the method .of the; present invention iwith those ob-i tainable according to the known methods, the advantages attained-by the method of the presentsinventiojn are clear;

Further, themethod of this'invention may be applied;

to molded articles. 4 The variation to be efiectedtorthis use resides in a suitable; regulation of the-viscosity of: the leuco-alkaline: solution of the vat dyestuffs by thi'ckening agents; v

The following examples will fu'rthera'illustrate ;thein- Examples 1-23; illustrate that embodiment' of 1 the dyestuff is applied asa solution vention, the invention wherein and is inleuco: form; V V EXAMPLE, :1

A sample of polypropylene fiber is impregnated (in a Foulardappaifatus) in anaaqueo'us bath;at'60 C., containing 25 g./l. of; brilliant-green Romatrene FFB (C-.1. t 59825) reducedfto leuco-alkaline= compound with' 42 I g./l-. of =51 36 B.:NaOHt i15 g./l.i'sodium hydrosulfite and i '25 -'g./;l. rof thet sodium salt of tdinaphthyl-methan erIv disulfonic 'acidli contains the sodium salt of oleylvmethyltaurinie acid and an'oxidizing ;agent-, namely, 30% hydrogen ;peroxide '(ooncentration '2 col/1.), rinsed, and dried;

Theufiberi'is dyed green with good uniformity and 1/ 1 intensity; according to :the ECB Standard scales (It? exhibits: good general fastness and fastness 1to natural i lightot-at'leastcone point 011:8 higherrthanathat for a dyeing obtained. on the same fiber using the a same idye- 'stug reduced :1 bath at 50? I Cganda pHj9;5-l0. EXAMPLEZ;

This example-is similarto Example 11, however there is addedito the impregnating bath "a suitable amount of additives to facilitate the penetration; and namely, 25 'g./l; of diethyl; tartrate,:

;the levelling, r and also thickening 1 -10 g./100 cc.).

dispersion.

. agents compatible with the bath, namely, Nafka rubber higher uniformity, a higher purity, and a brighter shade.

EXAMPLES 3-17 Byoperating as described in Example 1, using the dyestuifs reported in Table 1; results and advantages simil to those mentioned in Example 1 are obtained.

' Table 1 Example Dyestuflf Color Index Shade Number 3 Tomantrene yellow GCN 0.1. 67300--. Yellow. ctg ltfielri yellow Romantrene 0.1. 59105--- Do. Brilliant pink Romantrene FR. 0.1. 73360.-- Pink. Brli lzlifint violet Romantrene 0.1. 60010... Violet. Bromoindigo 2BD 0.1. 73065..- Blue. Brli liant green Romantrene 0.1. 59830... Green. Brown Romantrene FR or. 09015..- Brown. Brown Romantrene FBR 0.1. 70800-.. Do. Olive Romantrene FT 0.I. 69525.-. Olive. Yellow Romantrene FBRT 0.1. 70805.-- Yellow Olive Romantrene FR---- 0.1. 69005--- Olive. Blue Romant-rene FRS-.. 0.1. 09800.-. Blue. Blue Romantrene FGD... 0.1. 69810.- Do. 16..."-.- Blue Romantreue F130...- 0.I. 69825... D0.

17 Dark blue Romnntrene FBO... 0.1. 59800... Blue me.-

I rule.

EXAMPLE 18 By operating as described in Example 2 using each of the dyestuffs reported inTable 1, results are obtained which are similar to those reported in Example 2.

EXAMPLE 19 Example 1 were obtained.

\ EXAMPLE 20 By operating as described in each of Examples 2 and A 18, but using samples of compact polypropylene sheet,

results similar to those reported for Example 2 were obtained.

EXAMPLE 21 On a fabric of polypropylene fiber a printing is made,

- using a paste prepared as described in Example 2, but

using a higher amount of thickening agent (for instance 'The printed material thus obtained is finished as described in Example 1. Y Good printing results were obtained, ,as shown by good penetration, uniformity, and fastness and other characteristics similar to those for the articles dyed as described in Example 2.

EXAMPLE 22 By proceeding according to the method described in Example 21, using each of the dyestuffs reported in Table 1, results similar to those specified in Example 21 were obtained.

. EXAMPLE 23 EXAMPLE 24 A sample of polypropylene fiber is impregnated (using a Foulard apparatus) in an aqueous bath at 50-60" C. containing a dispersion of 25 g./l. of solid Brilliant green Romantrene (0.1. 59825) having a particle size less than i 1 micron, dispersed into the bath with 25 g./l. of an anionic dispersing agent (the sodium salt of the dinaphthylmethane-disulfonic acid).

The impregnated material is treated for 1 to 10 minutes in a suitable apparatus (a continuous polymerization reactor heated by hot air at -125" 0.), with an aqueous bath containing sodium hydroxide and sodium hydrosulfite, at 50-60 C., keeping the pH between 9.5 and 10 by gradual addition-of ammonium acetate, until the reduction of the vat dyestulf has been effected, is rinsed with cold water, soaped for 20-30 minutes with a solution at its boiling temperature, this solution containing the sodium salt of oleyl-methyl-taurinic acid and a suitable oxidizing agent (1-2 cc./l. of 30% hydrogen peroxide) rinsed, and dried.

The fiber is dyed green with a good uniformity at an intensity of 1/1 according to the standard ECE scale, and shows good general fastness and a fastness to natural light of at least one point on 8 higher than that when dyeing the same fiber using the same dyestuif reduced in a bath at 50 and pH 9.5-10.

EXAMPLE 25 EXAMPLES 26-35 By operating as described in Example 2A, using each of the dyestuffs reported in Table 2, results and advantages similar to those described in Example 24 are obtained:

Table 2 Example Dyestuti Color Index Shade Number 26...--." Yellow Romantrene GCN 0.1. 67300... Yellow.

BIE IIlEigt green Romantrene 0.1. 59830... Green. Brown Romnntrene FR....-. 0.1. 69015... Brown. Brown Romnutrene FBR 0.1. 70800-.- Do. Yellow Romuntrene F3R'I....- 0.I. 70805.-. Yellow.

Olive Romantreue FR 0.1. 69005 Olive. Blue Romantrene FRS 0.1. 69800... Blue. Blue Romnntrene FGl).. 0.1. 69810 Do. Blue Romantrene F 0.1. 69825... Do. Dark blue Romantrenc FBO- 0.1. 59800..- Do.

EXAMPLE 36 By operating as described in Example 25, but using.

each of the dyestuifs reported in Table 2, results similar to those of Example 25 are obtained.

EXAMPLE 37 EXAMPLE 38 On a polypropylene fabric a printing is performed using a paste prepared according to Example 25, but using higher amounts of thickening agent) 5 to 30 g./'100 cc.).

The material thus printed is treated for 6 minutes at 120-125" C., cooled andimptjegnated in a Foulard apparatus with-an alkaline solution of a thickened reducing agent (10 g. of starch as thickening agent, 'g.; sul-- i phoxylate formaldehyde, 15 'g. potassium carbonate, 60

I g. water), treated for 6 minutes at a temperature not higher than 125,, C., rinsed, soa'ped-at the boiling temperature,

rinsed again and dried.

Printing fabric is obtained which has a good degree of penetration, uniformity, and which has a fastness similar to those of the articles dyed in Example25.

' EXAMPLE 38 temporaneously oxidizing said ,dyestulf to thereby f oxidize :the idyestutf directly. while itis on=the polypropylene material. 3., The method of claim 1 wherein the oxidizing .is efffected using ahydrogen peroxide? :solutionhaving a;

volume concentration of about.30% hydrogen peroxide. 4. The, method of claim .1 wherein the .vat dyestufi is selected from the, group consisting of anthraqu inone dyestuds; indigo dyestufis, thioindigo, :dyestulfs, carbazole dyestulfs, benzanethrone dyestutfsg; and Lanthranthrone;

dyestulfs.

By'operating as described in Example 37, using the dye-' stufis reported in Table 2, similar results are obtained.

EXAMPLE 39 By operating as described in Example 37, but using the dyestutfs reported in Table 2 on a sample of a compact polypropylene sheet, similar results are obtained.

Variations. can of course be made without departing V T .from the spirit ,of this invention.

Having. thus described the invention, what is desired I to be secured and claimed'by Letters Patent is:.

1. A method for the dyeing and printing of a vat dyestufi on a shapedarticle of polypropylene, this method comprising:

(a), impregnating said polypropylene with atreating material selected from the group consisting ofa solu t I tion of a vat dyestutf in;alkaline leuco form v and. a dispersion of a vat dyestulf,

I (b)'removing theaimpregnated polypropylene from said treating material and heating said impregnated J polypropylene ata-temperature of fromabout 120 r ('c) where a dispersion'of a vat dyestuff is used in said impregnating step (a), reducing the dyestuff present in the heat treated, impregnated polypropylene to the l alkaline leuco form, and

(d) soaping said impregnated polypropylene with a soap solution at its boiling temperature while contemporaneously oxidizing said dyestufi.

2. A method for dyeing and printing of vat dyestuffs on polypropylene a shaped article of material comprisa) impregnating the polypropylene-material with a solution of a vat dyestuff in alkaline leuco form,

f (b) removing'the impregnated polypropylene from 1 said treating material andheat treating the impreg-t natedpolypropylene material at a temperature of 1 from about to C., and

(c) soaping said impregnated polypropylene with a a soap solution at its boiling temperature while con-- 5. A shaped articleiof polypropylene dyed according,

to the method of claim 2.

6.1 The method of claim2 wherein said impregnation of said polypropylene with a vat dyestutf in leuco form is carried out in the presence or an additive selected from the group,-consisting; of the sodium salt of ligninsulfonic acidgthe sodium salt ofnaphthalene sulfonicracid, the sodium saltmof dinaphthylmethane-disulfonic acid, and,

diethyl tartrate.-

7. A method fo'r dyeing and printing of vat dyestuff in the; dispersed state on a shaped article of polypropylene comprising:

(a) impregnating thepolypropylene; material with a dispersion of a vat dy'estufii, (b) removingthe impregnated. polypropylenev from said treating material and heat treating the impreg nated Epolypropylene material at a temperature of.

from about 1 20 to 125 'C., I .(c) reducing the dyestutf 10,1116 alkaline leuco form while on the polypropylene material, and

(d) oxidizing the dyestulf andcontemporaneously. I soaping the impregnated lpolypropylene -using a soap solution at its boiling temperature; a

8.: A shaped article of polypropylene dyed according to the'method of claim 7.1

9.,The method of cla'imf7 wherein-saidtirnpregnationof said polypropylene with a .vat dyestufi in leuco form is carried out in the presence of an additive selected from the group ;consisting of; the; sodium salt of ligninsulfonic acid, the sodium salt ofnaphthalene 'sulfonic acid, the

sodium rsaltia'of dinaphthylmethaneaiisulfonic acid, and diethyl tartrate.i

NORMAN G. TORCHIN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,233,960 February 8, 1966 Bruno Lonardo It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, lines 30 and 31, for oleyl-methyl-turinic" read oleyl methyl-taurinic Y column 4 line 17, for "to be known" read to known lines 68 and 69, for "dyestug reduced" read dyestuff reduced column 6, line 75, for "agent) 5 to 30" read agent [5 to 30 a column 7, line 44, strike out "on polypropylene a shaped article of" and insert instead on a shaped article of polypropylene column 8, line 21, for "printing of vat dyestuff" read printing of vat dyestuffs Signed and sealed this 7th day of February 1967. SEAL) Lttesti .RNEST W. SWIDER EDWARD J. BRENNER .ttesting Officer Commissioner of Patents 

1. A METHOD FOR THE DYEING AND PRINTING OF A VAT DYESTUFF ON A SHAPED ARTICLE OF POLYPROPYLENE, THIS METHOD COMPRISING: (A) IMPREGNATING SAID POLYPROPYLENE WITH A TREATING MATERIAL SELECTED FROM THE GROUP CONSISTING OF A SOLUTION OF A VAT DYESTUFF IN ALKALINE LEUCO FORM AND A DISPERSION OF A VAT DYESTUFF, (B) REMOVING THE IMPREGNATED POLYPROPYLENE FROM SAID TREATING MATERIAL AND HEATING SAID IMPREGNATED POLYPROPYLENE AT A TEMPERATURE OF FROM ABOUT 120 TO 125*C., (C) WHERE A DISPERSION OF A VAT DYESTUFF IS USED IN SAID IMPREGNATING STEP (A), REDUCING THE DYESTUFF PRESENT IN THE HEAT TREATED, IMPREGNATED POLYPROPYLENE TO THE ALKALINE LEUCO FORM, AND (D) SOAPING SAID IMPREGNATED POLYPROPYLENE WITH A SOAP SOLUTION AT ITS BOILING TEMPERATURE WHILE CONTEMPORANEOUSLY OXIDIZING SAID DYESTUFF. 